Fluid pressure brake control



Sept. 20, 1938.

55 64 \III .1. CANETTA ET AL 2,130,612 FLUID PRESSURE BRAKE CONTROLFiled Dec. 18, 1936 2 Sheets-Sheet 1 APPLICATION INVENTORS .JUHN EANETTAEARLE E. cum

ATTORNEY J. CANETTA ET AL FLUID PRESSURE BRAKE CONTROL Sept. 20, 1938.

Filed Dec. 18, 19 36 2 Sheets-Shet 2 @Q g 5 we on. 5 21 I 91 @Q 31 N3 m95 E Q 3 2 H w: \IMWNQ m J\m g AK STU RTU Y oEB E TN N N E W R E o v T.HR T D A E wmm Patented Sept. 20, 1938 PATENT OFFICE FLUID PRESSUREBRAKE CONTROL John Oanetta and Earle s. cook, Wilkinsburg,

Pa., assignors to TheWestinghouse Air Brake Company, Wilmerding,

Pennsylvania Pa., .a corporation of Application December 18, 1936,Serial No. 116,446

11 Claims.

This invention relates to brakes for railroad vehicles, and moreparticularly to the type operated by fluid pressure.

In effecting an application of the brakes on a long train, it isdesirable to avoid operation of the brakes on cars near the front end ofthe train too far in advanceof operation of those on the rear cars, inorder to prevent harsh slack take-up and resultant damage to equipmentand lading. With air brakes of the type operative upon a reduction inthe pressure of air in a brake pipe toeffect an application of thebrakes, it is sometimes difficult to transmit a pressure reductionWavethroughout the length of the brake pipe rapidly enough to effect thedesired uniform and safe operation of the brakes, due largely to theinertia characteristics of the compressed air in the brake pipe.

It is known that energy in the form of waves can be transmitted throughcertain mediums at rates greatly exceeding the speedof propagation ofwaves through air. For example, a pressure .wave can be propagatedthrough gaseous hydrogen at a rate of over four thousand feetper second,due to the inherent characteristics of that medium. Similarly, the wavespeed in water is also greater than four thousand feet per second. Oneobject of our invention is to provide an improved fluid pressure brakesystem for a train adapted to utilize a medium having a fast wave"propagation speed, such as hydrogen or water, for rapidly transmittingthe brake actuating pressure wave throughout the train, and brakingmeans on cars of the train adapted to respond to sucha wave so as toeffect the quick and substantially uniform operation of the brakes.

A further object of our invention is to provide a fluid pressure brakesystem adapted to utilize gaseous fluid having a high wave transmittingspeed, such as hydrogen, as an operating medium, and means forpreventing loss of the fluid from said system.

Another object of the invention is to provide a braking system for atrain comprising air operated braking means adapted to efiect theapplication and the release of the brakes, and apparatus associatedtherewith adapted to respond to waves propagated through a medium havinga faster wave transmission velocity than that of air for controlling theoperation of said means.

Other objects and advantages will appear in the following description ofthe invention, taken with reference to the accompanying drawings,wherein Fig. l is a diagrammatic view, mainly in section, of a fluidpressure brake apparatus embodying one former the invention; Fig. 2 is aplan View of the brake valve handle shown in Fig. 1; Fig. 3 is a diagramshowing the communications established in different positions of thebrake valve shown in Fig. 1; Fig. 4 is a diagrammatic sectional View ofa fluid pressure brake apparatus embodying another form of theinvention; Fig. 5 is a diagram showing the communications established invarious positions of the brake Valve device shown in Fig. 4; and Fig. 6is a sectional view of a brake control valvedevice constructed accordingto the invention and having service and emergency positions.

The fluid pressure brake system illustrated in Fig. 1 of the drawings isdesigned to employ suitable gaseous fiuid such as hydrogen as the wavetransmitting medium, and comprises an air brake pipe I adapted to benormally charged with compressed air, an operating brake pipe 2 adaptedto carry hydrogen under pressure, equipment mounted on the locomotiveincluding a brake valve device 4, acut-off valve device 5, a mainreservoir 6, a hydrogen reservoir 1, a hydrogen compressor 8 and adriving motor 9 therefore, and apparatus mounted on each car of thetrain comprising a brake control valve device l2, a brake cylinder l3and an auxiliary reservoir M.

The brake valve device 4 may be of any suitable type, and for thepurpose of illustration is shown in the drawings as having a releaseposition for controlling the supply of hydrogen to the operating brakepipe 2, a lap position, and an application position for effecting areduction in the pressure of hydrogen in the operating brake pipe. Thebrake valve device 4 comprises a casing having a valve chamber l6connected by Way of a passage and pipe [8 with the hydrogen reservoir 1,and a'rotary slide valve l9 mounted in the valve chamber and adapted tobe manually operated by means of a handle 20. A feed valve device 22 ofany suitable type is preferably interposed in the pipe l8 for supplyinghydrogen from the reservoir 1 at the desired pressure, and a stabilizingreservoir 23 may be connected by way of a branch pipe 24 to the pipe l8adjacent the outlet of the feed valve device to minimize the efiect ofpossible fluctuations in the pressure of hydrogen delivered by said feedvalve device.

A reduction reservoir 25 is provided for receiving hydrogen releasedfrom the operating brake 0 pipe by operation of the brake valve device 4as will hereinafter be described, said reservoir being connected by wayof a pipe 26 to the intake of the compressor 8, which is operative bythe motor 9' to compress the hydrogen and to supply it through a pipe 21to the hydrogen reservoir 1.

Means is provided for replenishing the supply of hydrogen in the systemin case of unavoidable loss of the gas due to leakage or other causes,comprising a hydrogen storage reservoir 29 which is adapted to carry asupply of hydrogen under high pressure. A valve 30 is interposed in thepipe 26 for normally isolating the storage reservoir 29, and is manuallyoperative to cut off com-' munication between the reduction reservoir 25and the compressor 8 while connecting the storage reservoir 29 throughsaid pipe to the compressor for permitting the desired additional supplyof hydrogen under pressure to the reservoir I.

A suitably insulated switch contact 3| is mounted on the brake valvehandle 20 and is adapted in the release position thereof to'bridge apair of contacts 32 for completing a circuit for the supply of currentfrom a source of electrical energy 33 to the motor 9, said circuitbeingfrom the source of current through conductor 34, switch contacts 3|and 32, a conductor 35, to the windings of the motor'9, and thence toground at 36. Suitable means (not shown) for controlling operation ofthe compressor, such as a compressor governor, may be provided ifdesired.'

It will be understood that the construction and arrangement of means forsupplying and conserving hydrogen in the system as just described isintended to be illustrative only, and that any other means formaintaining the desired supply of hydrogen under pressure in the trainpipe may be substituted if preferred, without departing from the spiritof the invention.

The cut-off valve device 5 comprises a casing having mounted therein a,diaphragm 38 forming a chamber 39 which is connected by way of a pipe 46with the air brake pipe I, and a diaphragm 4| having a larger pressurearea than the diaphragm 38 and forming a chamber 42, which communicatesthrough a pipe 43 with the reduction reservoir pipe 26. The diaphragms38 and M are connected by a stem 44, and the chamber intermediate thediaphragms is open to the atmosphere through a port 45. The diaphragm 38is engageable with a seat rib 46 to act as a valve for controllingcommunication between the chamber 39 and a pipe 41 which is connected tothe main reservoir 6, the diaphragm being normally urged away from theseat ribby a coil spring 48 surrounding the seat rib. The feed valvedevice 49 is interposed in the reservoir pipe 41 and is operative in thewell known manner to supply air under the pressure which it is desiredto maintain in the air brake pipe I.

The brake controlling valve device I2 comprises a triple valve portion50 and a pilotvalve portion 5|. The triple valve portion comprises acasing having a piston chamber 53 in which is mounted a piston 52, and avalve chamber 54, which is connected through a pipe 55 with the auiliaryreservoir I4. A main slide valve 51 and a graduating slide valve 58 aremounted in the valve chamber 54 and are adapted to be operated by thepiston 52 through the medium of a stem 59.

The pilot valve portion 5| of thedevice I2 comprises a casing havingmountedtherein. a

flexible diaphragm 6|, which forms on one side a hydrogen chamber 62communicating by way of a pipe 63 with the operating brake pipe 2, andhas on the other side a chamber 64, which is open to the piston chamber53 through an aper- 'ture 65 formed in a wall 66, Which separates the.69. projecting from the wall 66 within chamber 64 is a pilot supplyvalve II, having one end centrally secured to the diaphragm 6! by meansof a follower I2, which is applied to the opposite side of the diaphragmand has a bolt portion eX- tending therethrough and adapted to havescrew threaded engagement with the slide valve. The pilot slide valve IIis arranged to control communication from the piston chamber 53 and theair brake pipe I connected thereto to a reduction reservoir I3, ashereinafter explained.

It will be noted that the pilot slide valve TI is relatively smallandlight and is thus adapted to respond readily to operation of thesensitive diaphragm 6I. A coil spring 75 is interposed between the wall66 and the diaphragm 65 for urging the pilot slide valve II toward thelefthand, as viewed in the drawings, said valve being normallymaintained in the release position shown in the drawings by the pressureof a coil spring I6, which is mounted between the wall of the hydrogenchamber 62 and the follower i2 and is adapted to exert greater forcethan the spring I5.

In preparing the fluid pressure brake system for operation, compressedair is supplied from the main reservoir 6 by the usual operation of thefeed valve device 39 and flows through the pipe 41, past the normallyunseated diaphragm 38 in the cut-01f valve device 5, and through thechamber 39 and pipe 46 to the air brake pipe I, which is thereby chargedwith air at the desired normal pressure. Air under pressure is thensupplied from the air brake pipe I through the pipe 61 to the chamber 64in the brake control valve deviceIZ, and thence flows through theaperture 65 to the piston chamber 53; The pressure of air in the pistonchamber 53 forces the piston 52 to the release position, as shown in thedrawings, and air under pressure is then supplied from said chamberthrough the usual feed groove I8 to the valve chamber 53 and theconnected auxiliary reservoir I4. With the triple valve parts in releaseposition, the brake cylinder I 3 is connected to the atmosphere througha pipe 19, passage 80, a cavity 8! in the main slide valve 5'! and anexhaust port 82.

Any desired means may be employed to charge the operating brake pipeinitially with substantially pure hydrogen, after the cars have beenassembled into a train in the railway yard. For example, the operatingbrake pipe 2 may be initially charged with hydrogen before thelocomotive is coupled to the train, by first connecting the pipe to asuitable suction pump, not illustrated, for creating a partial vacuum inthe pipe, and then supplying hydrogen under pressure thereto from anoutside source, after which the locomotive may be coupled to the trainfor maintaining the desired pressure of hydrogen in the followingmanner.

While the air brake system is being charged with compressed air as abovedescribed, hydrogen under substantially the same pressure'as that of theair in the air brake pipe I is supplied from the hydrogen reservoir 1 tothe pipe It by the automatic operation of the feed valvedevice 22. Thehydrogen under pressure is also supplied through the pipe 24 to thestabilizing reservoir 23. With the brake valve device 4 in releaseposition, hydrogen flows from the pipe 18 to the chamber I6 of the brakevalve device and thence through port 85 in the rotaryvalve l9, to apassage and pipe 88 and the operating brake pipe 2.

As hereinbefore explained, with the brake valve handle in releaseposition and the circuit to the motor 9 thus completed, the compressor 8is rendered operative to maintain the reduction reservoir free ofhydrogen and under a partial vacuum.

Hydrogen under pressure is then supplied from the operating brake pipe 2through the pipe 63 to the hydrogen chamber 62 in the brake controlvalve device l2 on each car of the tran. The pressure of the hydrogen inthe chamber 62 being substantially equal to the brake pipe pressureacting in the chamber 64, it is apparent that the diaphragm BI andassociated pilot slide valve II will be maintained in the releaseposition by the spring 16 as already explained. Inthis position of thepilot slide valve, the reduction chamber 13 is connected to theatmosphere by way of a pipe 90, a passage 9| having .a restrictedportion 92, a cavity 93 in the slide valve and an exhaust port 94.

When it is desired to effect an application of the brakes, thehandle 20of the brake valve device 4 is moved to the application position whereinthe connection between chamber 16 and passage 86 is lapped, while acavity 95 in the rotary valve T connects the passage 86 with a passage96 as is indicated in Fig. 3 of the drawings. Hydrogen under pressure isthen vented from the operating brake pipe 2 by way of the pipe andpassage 86, cavity 95, passage and pipe 96, and pipe 26 to the reductionreservoir 25. At the same time, hydrogen under pressure thus suppliedfrom the operating brake pipe 2 to the pipe 26 flows therefrom throughthe pipe 43 to the chamber 42 in the cut-off valve device 5, and movesthe diaphragm 4|, the follower 44 and the diaphragm 38 upwardly againstthe pressure of the spring 48 and of the air acting on the smaller areaof said diaphragm 38, so that said diaphragm engages the seat rib 4B forpreventing further supply of air under pressure to the brake pipe I.

Due to the ability of the hydrogen to propagate the pressure reductionwave at a fast rate, the pressure reduction wave initiated as justexplained is quickly transmitted through the hydrogen in the operatingbrake pipe 2 and causes a corresponding reduction in the pressure of thehydrogen acting in the chamber 62 in the brake control valve device' l2on each car in the train. The diaphragm iii and the pilot slide valve llcontrolled thereby are designed to respond to slight pressurevariations, and the initial reduction in the pressure of hydrogen in thechamber 52 is suflicient to permit the pressure of air in the chamber54, as aided by the force of the spring '55, to cause the diaphragm toshift the pilot slide valve H to a brake pipe venting position. With thepilot slide valve II in venting position, the connection between thepassage 9! and the atmosphere is cut off and the cavity 91 is broughtinto registration with a passage 98 communicating with the pistonchamber 53.

Air under pressure is then vented from the air brake pipe I by way ofthe pipe 61, chamber 64, aperture 65, piston chamber 53, passage 98,cavity 3i and passage 91 to the reduction reservoir 13.

As the pressure of air in the chamber 53 is thus reduced, the pressureof the air in the valve chamber 54 in the triple valve portion 50 causesoperationof the piston 52 to close the feed groove 18, and to move theauxiliary slide valve 58 relative to the main slide valve 51 foruncovering a service port I00 in said main slide valve. Continuedmovement of the piston 52 brings a lug it! formed on the stem 59 intoengagement with the main slide ,valve 51, which is then shifted intoapplication position. With the triple valve parts in applicationposition, air under pressure is supplied from the auxiliary reservoir byway of the pipe 55, valve chamber 54, the service port I99 in the mainslide valve, port 80 and pipe l9 to the brake cylinder l3, therebyeffecting an appli cation of the brakes. i

Meanwhile, when the pressure of hydrogen in the operating brake pipe 2has been reduced sufficiently, by operation of the brake valve device 4as already described, to effect the desired degree of application of thebrakes, said brake valve device is moved into lap position, whereinfurther venting of hydrogen from the operating brake pipe is cut off.When the pressure of air in the piston chamber 53 of the brake controlvalve device I2 and in the connected valve chamber 64 has been reducedby flow to the reduction reservoir 13 to a Value slightly less than thatof the hydrogen pressure acting in the chamber 62, the flexiblediaphragm BI is forced to the release position as shown in the drawingsby the pressure of the spring 16 and of the hydrogen in the chamber 52.In so moving diaphragm 6i shifts the pilot slide valve H to its releaseposition, in

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which further venting of air from the brake is prevented.

Further reduction in the pressure of air in the chamber 53 is thusprevented, and when continued supply of air under pressure from theauxiliary reservoir I4 and chamber 54 to the brake cylinder'reduces theair pressure in said chamber slightly below that in chamber 53, thepiston 52 will be operated so as to shift the auxiliary slide valve 58into lap position wherein the service port Hi9 in the main slide valve51 is lapped, thus cutting off further supply of air from the auxiliaryreservoir 14 to the brake cylinder I3.

When it is desired to effect the release of the brakes, the handle 20 ofthe brake valve device 24 is moved to release position, thereby causingthe rotary valve l9 to establish communication, as already described,permitting the supply of hydrogen under pressure from the main hydrogenreservoir to the operating brake pipe 2. At thesame time, the contact 3icarried on the han dle 2B is brought into engagement with the contacts32, thereby completing the circuit through which current is supplied tothe driving motor 3, which then operates the hydrogen compressor 8 forwithdrawing hydrogen under pressure from the reduction reservoir 25 byway of the pipe 25 and supplying said hydrogen under pressure throughthe pipe 2? to the hydrogen reservoir i.

As the pressure in the reduction reservoir 25 pipe 40 to the brake pipeI. Air under pres-' sure thus supplied to the air brake pipe I flowstherefrom through the pipe 6'! to the connected chambers 64 and 53 inthe brake controlling valve device I2 and operates the piston 52 toshift the main slide valve 51 to the release position, wherein the brakecylinder I3 is again connected to the atmosphere through the pipe I9,passage 80, cavity 6| in said slide valve and the exhaust port 82.

Referring to Fig. 4 of the drawings, there is illustrated another formof our invention embodying fluid pressure brake apparatus adapted toemploy a liquid, such as water, as the medium through which the brakecontrolling impulse or pressure reduction wave may be transmittedthroughout the train.

The apparatus shown in Fig. 4 of the drawings is adapted to be mountedon the locomotive and includes an air brake pipe; I05, an operatingbrake pipe I06, a brake valve device I01, a main reservoir I08 and aliquid reservoir I09. The operating brake pipe I06 is adapted to besupplied with liquid and is connected through a pipe III with thelowermost portion of the liquid reservoir I09, which is adapted tocontain a body of liquid that may be supplied as needed from a liquidsupply tank II2 by operation of a control valve II3 interposed in a pipeII4 connecting said tank with the reservoir.

The brake valve device I01 is adapted to control the supply of air underpressure to the brake pipe I05, and also to control the air pressureexerted on the liquid in the reservoir I09. The brake valve device I01comprises a casing having a valve chamber II5 connected through apassage H6 and a pipe II! to the main reservoir I08, and having mountedtherein a rotary valve II8 which is adapted to be operated through themedium of the usual handle H9. The rotary valve H8 is provided withacavity I ZI, which is open to the valve chamber II5. With the rotaryvalve in release position as shown in Fig. 4, the cavity I 2I isconnected by way of a passage and pipe I22 with the air brake pipe I05,and also by way of a passage and pipe I23 with the liquid reservoir I09.

While the apparatus adapted to be mounted upon the cars in the train isnot included in Fig. 4 of the drawings, it will be understood that theequipment there shown is adapted to be associated with suitableapparatus including a brake control valve device, a brake cylinder andan auxiliary reservoir, the brake control valve device being preferablythat shown in Fig. 6.

Referring to Fig. 6 of the drawings, there is illustrated a form ofbrake control valve device designed for association with the apparatusshown in Fig. 4, and which may be operated on substantially the sameprinciple as the brake control valve device I2 shown in Fig. '1 butwhich includes means responsive to pressure reduction waves of differentintensities propagated through the wave transmitting medium, foreffecting either service or emergency applications of the brakes.

The brakes control valve device shown in Fig. 6 comprises a pilot valveportion I32 and a triple valve portion I33. Mounted in the pilot valveportion I32 is a flexible diaphragm I34, which forms on one side achamber I35 communicating through a pipe I36 with the operating brakepipe I06 adapted to contain the pressure wave transmitting medium, andwhich diaphragm forms on the other side a valve chamber I3'I that isconnected by way of a pipe I38 with the air brake pipe I05. Forcontrolling communication through which air under pressure may be ventedfrom the brake pipe there is provided a pilot slide valve I39, which hasone end centrally secured to the diaphragm I34, and is slidably mountedin a valve seat portion I40. A coil spring I42 is disposed in thechamber I3? for urging the diaphragm I34 and the pilot slide valve I39toward the left-hand, and a coil spring I43 is interposed betweenthe-wall of the chamber I35 and the diaphragm I34 and acts on saiddiaphragm in opposition to the spring I42. The spring I43 is adapted toexert a greater force than the spring I42, so that the diaphragm I34 andthe pilot slide valve I39 are normally maintained in the releaseposition, as shown in Fig. 6 of the drawings.

It is not deemed necessary to illustrate the triple valve portion I33 indetail, it being understood that any of the well known triple valveconstructions may be provided, having means adapted to respond tovariations in brake pipe pressure for effecting either service oremergency applications of the brakes. which means may include a triplevalve piston I44 which is subject to the pressure of air in a chamberI45 con nected through a passage I46 and the chamber I3'I with the airbrake pipe I05.

In operation, air at the pressure normally carried in the fluid pressurebrake system is supplied from the main reservoir I08 shown in Fig. 4 ofthe drawings to the pipe II? by the usual operation of the feed valvedevice I25, which is similar to the feed valve device 49 shown inFig. 1. From the pipe III, air under pressure is supplied through thepassage II6 in the brake valve device III'I to the valve chamber H5, andthence flows through the cavity I2I in the rotary valve H8 and throughthe passage and pipe I22 to the air brake pipe I05. Air under pressurefrom the cavity I2I is also supplied through the passage and pipe I23 tothe water reservoir I09, thereby subjecting the liquid therein and inthe operating brake pipe I06 to substantially the same pressure as thatnormally maintained in the air brake pipe I05.

It will be understood that upon the increase in the pressure of air inthe air brake pipe I05 and of the liquid in the operating brake pipeI06, the brake control valve device illustrated in Fig. 6 will beoperated to its release position, the connected chambers I31 and I45 inthe brake control valve device being supplied with air under pressurefrom the air brake pipe I05 by way of the pipe I38, while liquid issupplied from the operating brake pipe I06 through the pipe I36 to thechamber I35.

Suitable means may, of course, be provided for preventing entrapment ofair above the liquid within the chamber I 35. Each control valve devicemay have an automatic release valve, not shown; such as the well knowntype comprising a floating check valve which may control an atmosphericcommunication from the chamber I35 and may be adapted to be floated intoseated position for preventing escape of liquid through thecommunication. A float valve of the above type is illustrated in the U.S. Patent No. 1,660,466 to B. S. Aikman. It will also be understoodthat, when the train pipe and control valve on a car have once beencharged with liquid, the liquid may be retained therein even when thecar is not connected in a train,

by proper operation of the usual train pipe cutout cocks, not shown. l I

In order to effect a service application of the brakes, the handle H9 ofthe brake valve device I91 is moved to service position, wherein acavity I21 in the rotary valve H8 registers with the passage I23 andwith a restricted atmospheric exhaust passage I28, thereby effecting reduction in the pressure of air contained above the liquid in thereservoir I99 at a slow or service rate. It will be noted that with thebrake valve device M1 in service position, the communication between thevalve chamber I I and the passage I22 is cut off, so that further supplyof air under pressure from the main reservoir I93 to the air brake pipeI95 is prevented.

As a result of the service rate of reduction. in the pressure of airacting on the liquid in the reservoir I99 as just described, a pressurereduction wave is initiated in the liquid in the operating brake pipeI96, and is rapidly transmitted therethrough for actuating the brakecontrol valve devices such as that illustrated in has to effect aservice application of the brakes.

The pressure wave thus initiated in the operating brake pipe causes areduction in the pressure of liquid in the chamber I35 of the deviceshown in Fig. .6 at a service rate, so that the pressure of air in thechamber I31 and of the spring I42 is permitted to move the diaphragm I34and the pilot slide valve I39 toward the left-hand, until a cavity I48formed in the slide valve establishes communication between a passageI49 and an atmospheric exhaust passage I59 having a restricted portionI5I. Air under pressure is then vented from the brake pipe 95 toatmosphere by way of the pipe I38, the chamber I31, the chamber I45connected thereto, the passage I49, the cavity I43, and the exhaustpassage I59 and restricted portion I5I, the consequent reduction in. thepressure of air acting in the chamber I31 against the diaphragm I34being such as to prevent further movemfint of saiddiaphragm and of thepilot slide valve I39 toward the left hand. Upon the reduction in thepressure of air in the chamber I45, the piston I44 is operated in theusual manner to move the triple valve parts (not shown) to serviceposition for effecting a service application of the brakes.

If it is desired to effect an emergency application of the brakes, thebrake valve device I91 shown in Fig. 4 of the drawings ismoved to theemergency position, in which a. cavity I29 in the rotary valve H8connects the passage I23 with an atmospheric exhaust port I39, whilecommunication from the main. reservoir I98 to the air brake pipe I95 iscut off, as is best shown in Fig. 5 of the drawings. Air under pressureis then vented from the reservoir I09 through the pipe andpassage I23,the cavity L29 in the rotary. valve H8, and the atmospheric exhaustpassage I39 at an emergency rate, thereby causing a sudden reduction inthe pressure of the liquid in said reservoir in the operating brake pipeI99, so that a pressure reduction wave of emergency intensity is rapidlytransmitted through said pipe for effecting operation of the brakecontrol valve devices to their emergency positions. As the pressure :ofthe transmitting fluid in the operating brake pipe I96 and in.

the chamber L35 of the brake control valve .de-

in the chamber I31, aided by the force of the spring I42, acts to movethe diaphragm I34 and the pilot slide valve I39 to the emergencyposition, overcoming the force of the spring I43. With the pilot slidevalve I39 in emergency position, the cavity I48 therein connects thepassage 149 with a large exhaust passage: I53, so that air underpressure is quickly vented to atmosphere from the chamber I45 and fromthe air brake pipe I95 connected thereto by flow of air through thepassage I49, the cavity I48 and said exhaust passage at a fast rate,whereupon said triple valve piston I214 and the associated parts of thetriple valve portion I33 are operated in the usual manner to effect anemergency application of the brakes.

It will thus be evident that our invention provides a fluid pressuresystem adapted to be employed on a long train, and including air brakemeans and actuating means located on cars of the train responsive tovariations in the pressure of a fluid medium having the property oftransmitting energizing waves at a fast rate. for

controlling the operation of the air brake means,

together with means for controlling the supply and release of said fluidmedium in the system.

While several illustrative embodiments of our invention have beendescribed in detail, it is not our intention to limit its scope to theseembodiments orotherwise than by the terms of the appended claims.

Having-now described our invention, what we claim as new and desiretosecure by Letters Patent, is:

1. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valve meansoperative upon a reduction in the pressure of air in said brake pipe foreffecting an application of the. brakes, a train pipe normally chargedwith a fluid medium having the property of propagating waves of pressurevariation at a speed higher than that inair, pilot valve means operativeupon a reduction in the pressure of said fluid medium in the train pipefor venting air under pressure from the brake pipe, manually controlledmeans operative ;to effect a reduction in the pressure of thefluidmedium in said train pipe, and means controlling the supply of airto the brake pipe and operative in response to operation of saidmanually controlled means for cutting off said supply;

'2. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valve meansoperative upon a reduction in the pressure of air in said brake pipe foreffecting an application of the brakes and upon an increase in thepressure of air in-said brake pipe for effecting the release of thebrakes, a trainpipe adapted to be supplied with a fluid medium havingthe property of propagating waves of pressure variation at a speedhigher than that in air, pilot valve means operative in response to areduction in the pressure of the fluid medium in said train pipe forventing air underpressure from said brake pipe, a brake valve deviceoperable to discharge a quantityiof said fluid medium from the trainpipe to a chamber for initiating a wave of pressure reduction in saidfluid medium, and means controlling the supply of air under pressure tothe brake pipe and operative upon an increase in fluid pressure in saidchamber for cutting off said supply. i

3. In .a fluid pressure brake, in combination,

a brake pipe normally chargedwith air under pressure, braking meansincluding a brake control valve device operative upon a service rate ofreduction in brake pipe pressure to efiect a service application of thebrakes and upon an emergency rate of reduction in brake pipe pressure toeffect an emergency application of the brakes, a train pipe normallycharged with a fluid medium having the property of propagating waves ofpressure variation at a velocity greater than that in air, and pilotvalve means subject to the pressure of said fluid medium in the trainpipe, said pilot valve means being operative upon a wave of variation inthe pressure of said fluid medium of low intensity to vent air from saidbrake pipe at a service rate, and upon a wave of pressure variation insaid fluid medium of greaterintensity to vent air under pressure fromsaid brake pipe at an emergency rate.

4. In a fluid'pressure. brake system, in combination, an air brake pipe,means for supplying air under pressure to said air brake pipe, brakecontrolling valve means operative upon a reduction in the pressure ofair in said air brake pipe for effecting an application of the brakes,an operating brake pipe normally charged with a fluid medium having theproperty of propagating waves of pressure variation at a speed higherthan that in air, pilot valve means operative upon a reduction in thepressure of said fluid medium in the operating brake pipe for ventingair under pressure from said air brake pipe, means operative to effect areduction in the pressure of the fluid medium in said operating brakepipe, and means automatically operative to out off the supply of air tosaid air brake pipe when the pressure of said fluid medium in saidoperating brake pipe is reduced.

5. In a fluid pressure brake system, in combination, an air brake pipe,means for supplying air under pressure to said air brake pipe, brakecontrolling valve means operative upon a reduction in the pressure ofair in said air brake pipe for effecting an application of the brakes,an operating brake pipe adapted to be supplied with a fluid mediumhaving the property of propagating waves of pressure variation at aspeed higher than that in air, means for subjecting said fluid medium inthe operating brake pipe to the pressure of air in said air brake pipe,pilot valve vmeans responsive to a pressure reduction wave transmittedthrough the fluid medium in said operating brake pipe for venting airunder pressure from said air brake pipe, and controlapparatus operativeto initiate the pressure reduction wave in said fluid medium in theoperating brake pipe and to cut oiT the supply of air under pressure tosaid air brake pipe. V

6. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valve meansoperative upon a reduction in the pressure of air in said air brake pipefor efiecting an application of the brakes, an operating brake pipenormally charged with a fluid medium having the property of propagatingwaves of pressure variation at a speed higher than that in air, pilotvalve means operative upon a reduction in the pressure of said fluidmedium in the operating brake pipe for venting air under pressure fromsaid air brake pipe, brake valve means operable to dis charge a quantityof said fluid medium from the operating brake pipe toa reductionreservoir for initiating a wave of pressure reduction in said fluidmedium, andmeans including a compressor operative to supply fluid mediumfrom said reduction reservoir to the operating brake pipe.

7. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valve meansoperative upon a reduction in the pressure of air in said brake pipe foreifecting an application of the brakes, an operating brake pipe normallycharged with a fluid medium having the property of propagating waves ofpressure variation at a speed higher than that in air, pilot valve meansoperative upon a reduction in the pressure of said fluid medium in theoperating brake pipe for venting air under pressure from said air brakepipe, means operable to discharge a quantity of said fluid medium fromthe operating brake pipe to a chamber for initiating a wave of pressurereduction in said fluid medium, and fluid medium supply apparatusincluding a reservoir adapted for communication with the operating brakepipe and a compressor having inlet communication with said reductionchamber and outlet communication with said reservoir.

8. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valve meansoperative upon a reduction in the pressure of air in said air brake pipefor effecting an application of the brakes, an operating brake pipenormally charged with a fluid medium having the property of propagatingwaves of pressure variation at a speed higher than that in air, pilotvalve means operative upon a reduction in the pressure of said fluidmedium in the operating brake pipe for venting air under pressure fromsaid air brake pipe, brake valve means operable to discharge a quantityof said fluid medium from the operating brake pipe to a reductionreservoir for initiating a wave of pressure reduction in said fluidmedium, a supply reservoir from which the fluid medium is supplied tothe operating brake pipe and a compressor operative to supply fluidmedium from said reduction reservoir to said supply reservoir.

9. In a fluid pressure brake system, in combination, a brake pipe, meansoperative upon a reduction in brake pipe pressure for effecting anapplication of the brakes, a reduction reservoir, a brake valve deviceoperative to vent fluid from said brake pipe to said reductionreservoir, a supply reservoir from which fluid issupplied to said brakepipe, and a compressor for supplying fluid from said reduction reservoirto said supply reservoir.

10. In a fluid pressure brake, in combination, a brake pipe normallycharged with air under pressure, braking means including a brake controlvalve device operative in response to diflerent degrees of reduction inbrake pipe pressure to effect application of 'the brakes correspondingin degree to the rate at which brake pipe pressure is reduced, a trainpipe normally charged with a fluid medium having the property ofpropagating waves of pressure variation at a velocity greater than thatof air, and pilot valve means subject to the pressure of said fluidmedium in the train pipe, said pilot valve means being operative inresponse to a wave of variation in the pressure of said fluid medium tovent air from said brake pipe at a rate corresponding to the intensityof the wave of pressure variation in said fluid medium.

11. In a fluid pressure brake system, in combination, a brake pipenormally charged with air under pressure, brake controlling valvemeansfluid medium in said train pipe for venting air under pressure fromsaid brake pipe, and control apparatus operative to effect suddenwithdrawal of a quantity of said fluid medium from the train pipe and tocut off the supply of air to said brake 5 JOHN CANETTA. EARLE s. COOK.

